1. Field of the Invention
This invention relates to a remote control device, and more particularly to a remote control device used for a radio control transmitter and receiver system for a model drive unit or an industrial drive unit, such as, for example, a crane, a pile driver or the like.
2. Description of the Prior Art
A transmission system for driving and controlling a radio-controlled drive unit generally uses a pulse position modulation (PPM) system which generates a signal having a pulse width corresponding to movement of joysticks provided in a transmitter for transmission or a pulse-code modulation (PCM) system which generates a series of pulse code signals corresponding to movement of sticks in the transmitter for transmission. In general, the PCM system is extensively used, because it has less generation of noise and radio interference as compared to the PPM system.
However, in the conventional PCM system, it is required to limit a bandwidth of a transmitted signal so as to prevent radio interference. However, this results in a significant increase in a transmission time, because the conventional PCM system feeds an absolute data for determining the amount of control of each movable control of the drive unit for every channel corresponding to movement of the joysticks. In order to solve such a problem, there is proposed to expand the bandwidth to increase a data transmission rate. However, this is practicallY impossible, because the bandwidth must be limited as explained hereinabove. As a result, a response of the controlled drive unit is delayed.